Question

The aerodynamic centre of a subsonic airfoil is located at

• A. Leading edge
• B. \(25\%\) of chord from leading edge
• C. \(50\%\) of chord
• D. Trailing edge

Hint:

For different flow regimes, \[ \boxed{ \begin{aligned} \text{Subsonic airfoil} &\rightarrow 0.25c \text{Supersonic airfoil} &\rightarrow 0.50c \end{aligned} } \] The aerodynamic centre is the point about which the pitching moment is nearly constant.

Answer 1

The Correct Option is B

Step 1: Recall the definition of aerodynamic centre. The aerodynamic centre is the point on an airfoil about which the pitching moment remains nearly constant with changes in angle of attack.

Step 2: Locate the aerodynamic centre. For a subsonic airfoil, \[ \boxed{ \text{Aerodynamic Centre} = 0.25c } \] where \(c\) is the chord length. Thus, it is located at \[ \boxed{25\% \text{ of the chord from the leading edge}.} \] Therefore, \[ \boxed{(B)} \] is the correct answer.